The present invention relates to an oil supply apparatus for use with copying machines.
In a copying machine in which image fixing is effected by rollers, it is necessary to coat an offset preventing oil, such as silicon oil (hereinafter simply referred to as the oil), on an image fixing roller in order to prevent the offset of toner images.
Conventionally, an oil tank for holding the oil therein is located near a heated image fixing roller. Therefore, the oil in the tank is heated and evaporated and deteriorated, with the viscosity of the oil changing during storage of the oil in the tank, so that after a time, a desired offset preventing effect cannot be obtained from the oil. In order to remove such a shortcoming of the conventionl oil tank, an improved oil supply apparatus is known, in which the oil tank is located at a position away from the image fixing roller and a reservoir for holding a predetermined amount of the oil is located between the oil tank and the image fixing roller. The oil is supplied from the reservoir to the image fixing roller and as the oil in the reservoir is decreased, the oil is replenished from the oil tank into the reservoir. However, even in the case of this oil supply apparatus, the oil stays in the reservoir for a comparatively long time and it is inevitable that the oil is heated and evaporated and that the properties of the oil are changed. Furthermore, when the copying machine is moved, the oil tank has to be detached from the copying machine and the reservoir has to be evacuated.